Field of the Invention
The present invention relates to an image pickup apparatus including a display for displaying an image being shot.
Description of the Related Art
Conventionally, in the field of image pickup apparatuses such as digital video cameras and digital cameras, those with displays for use in checking of object images being shot, such as liquid crystal or organic electro luminescence displays (panels) or electronic view finders (EVFs), have been widely diffused.
The use of a display allows display of an object image being shot by a user, i.e., an image being recorded, on the display screen in real time with a predetermined image quality. However, the recent increase in the number of, pixels of a recorded image, and of image quality improvement functions has led to an elongated signal processing time, which in turn causes a display delay. A display delay causes the user to get an awkward feeling during camera operations such as panning, tilting, and zooming. This makes it difficult for the user to check a composition or a focus state.
The display delay amount depends also on the shooting frame frequency. The lower the frame frequency, the larger the delay amount is. Depending on the configuration of an image pickup apparatus, for example, if the frame rate is 24 Hz, the delay amount is two and a half times larger than in the case where the frame rate is 60 Hz.
Television apparatuses also suffer like problems due to the increased number of image quality improvement functions. Image quality improvement functions performed by a television apparatus when a game is played with the television apparatus being connected to a game player may result in a display delay of multiple frame times. This display delay results in a change in the results of the game or cause the user to get an awkward feeling. In order to reduce display delay, two methods are proposed in Japanese Patent No. 4691193. One is the method for performing processing to decrease display delay with simplified image quality improvement processes, and the other is the control method for concurrently performing the recording and reading of a frame memory.
However, the configuration described in Japanese Patent No. 4691193 is not intended for image pickup apparatuses, but for video display devices for displaying input signals such as televisions, and thus inevitably causes a delay time of one frame or more. Conventional technologies have, in their applications to image pickup apparatuses and other similar apparatuses, difficulties in the reduction of display delay time which occurs when an image being shot is displayed on their display devices.